Ignition system for multi-cylinder internal combustion engines

ABSTRACT

An ignition system for multi-cylinder internal combustion engines is disclosed, which comprises a plurality of electrically independent, ignition power generating coils wound on respective main cores arranged side by side along a line at right angles to the rotor shaft of a magnet generator, said main cores being magnetically coupled with a pair of auxiliary cores arranged such that the magnet flux from the magnet pole pieces of said magnet generator pass by these auxiliary cores. The ignition power generating coils are each connected in parallel to an ignition coil and with an interrupter switch.

United States Patent 091 Fu'ii 1 1March 13, 1973 I 1 IGNITION SYSTEM FORMULTI- 1,620,060 3/1927 Billon et al. ..123 149 1) CYLINDER INTERNALCOMBUSTION s t k aa ENGINES 2,990,112 6/1961 Levy et al. [75] Inventor:Hideo Fujii, Kariya, Japan 3,566,851 3/1971 Pfrommer 3,495,579 2/1970Davalillo ..123/l49 R [73] Assrgnee: Nlppondenso Co., Ltd., Kariya-shi,

Alchl'ken' Japan Primary Examiner-Laurence M. Goodridge 22 il Mal-ch 101971 Assistant ExaminerCort Flint Attorney-Cushman, Darby & Cushman [21]App]. No.: 122,982

[57] ABSTRACT Foreign Application Priority Data An ignition system formulti-cylinder internal com- March 13,1970 Japan ..45 24s14 busticlelgines is dimmed which Comprises a P rality of electricallyindependent, ignition power 52 us. (:1. .123/149 0, 310/153 generatingmils Wmmd respective was 51 Im. c1 ..F02p 1/02 ranged side by Side aangles [58] Field of Search .....123/148 E,' 148 DC, 148 AC, rolforShaft f a magnet generator, sa d main (.;(')res 123/149 K149 13,149 A,148,149; being magnetically coupled with a pair of aux1l1ary 310/156 154153 67 cores arranged such that the magnet flux from the 1 magnet polepieces of said magnet generator pass by [56] References Cited theseauxiliary cores. The ignition power generating v coils are eachconnected in parallel to an ignition coil UNITED STATES PATENTS and withan interrupter switch.

1,022,832 4/1912 Durbin ..123/149 D 3 Claims, 9 Drawing Figures 'llllll1m it "lIllIlllll mm. 3191s SHEET 2 OF 2 1N VENTOR ATTORNEYS IGNITIONSYSTEM FOR MULTI-CYLINDER INTERNAL COMBUSTION ENGINES This inventionrelates to a magnet-type ignition systems for multi-cylinder internalcombustion engines.

In the magnet-type ignition system without an ignition distributor formulti-cylinder internal combustion engines, a plurality of ignitionpower generating coils should be provided in the magnet generator inorder to ensure the ignition of air-fuel mixture in the respectivecylinders. Particularly, where the magnet generator also includes powergenerating coils for lighting and charging purposes, and where aplurality of ignition coils are used for individual cylinders, as, forinstance, in two-cycle multi-cylinder engines, a plurality ofelectrically independent, ignition power generating coils should beprovided in such a manner that each N-S pole pair of the rotor of themagnet generator has substantially a uniform influence on all thesecoils.

A typical example of the well-known ignition system of the kind, towhich the invention pertains, will now be described in detail withreference to the accompanying drawing, in which:

FIG. 1 is a fragmentary sectional view showing a magnet generator in theconventional magnet-type ignition system;

FIG. 2 is an enlarged perspective view ofa main part of the magnetgenerator shown in FIG. 1;

FIG. 3 is a view similar to FIG. 1 showing an example of the state ofthe conventional magnet generator mounted on an actual engine;

FIG. 4 is an end view, partly in section, showing a magnet generatorused in the ignition system according to the invention;

FIG. 5 is a sectional view taken along line V V in FIG. 4;

FIGS. 6, 7 and 8 are partial perspective views showing examples of theignition power generating coil to be mounted in the magnet generator ofthe ignition system according to the invention; and

FIG. 9 is a circuit diagram showing the circuit connection of theignition system according to the invention.

Referring now to FIGS. 1 and 2, there is shown a conventional magnetgenerator construction, in which electrically independent, ignitionpower generating coils 7 and 7' are provided. The coils 7 and 7 arerespectively wound on separate cores l5 and These coil units arearranged side by side along rotor shaft 16 with spacer l4 interposedbetween them. They are secured to support base 13 by means of bolts 9.

The magnet generator of the construction described above, however,presents various problems. With this construction, if it is intended todisassemble or replace one ignition power generating coil unit, forinstance coil 7, the other ignition power generating coil unit shouldalso be disassembled. Also, since the coil units are first stackedtogether, then secured to the support base 13 by bolts 9 and thereaftermachine finished so as to provide a predetermined gap between the coresI5 and 15' on one hand and the pole pieces 3 of the rotor on the otherhand, it is extremely difficult to successfully reassemble thedisassembled coil unit.

Further, from the aspect of cost, the cores 15 and 15' are usually madeof a lamination of expensive silicon steel plates because of highfrequency transient phenomena involved in the operation of thegenerator. Because the cores l5 and 15' have a narrow central portionwrapped with the coil and wider end portions, a great deal of extra orwaste material is required, thus resulting in increased material cost.

Furthermore, since the cores 15 and 15' of the core units are spacedapart by the spacer 14, the pole pieces 3 of the rotor should have anincreased area to cover the corresponding face of the coil units. If theignition power generating oils 7 and 7' are obliged to be arranged suchthat they axially deviate from the pole pieces 3 of the rotor due to,for instance, an obstacle 17 on the engine side as shown in FIG. 3,extreme unbalance between the outputs of the coils 7 and 7' is likely toresult, which is a fatal disadvantage from the aspect of ignitionperformance. Also, where three or more ignition power generating coilsare employed, the axial dimension of the rotor and hence the rotor shaft16 should be increased, which is very disadvantageous from the aspectsof engine design and engine appearance.

An object of the invention, accordingly, is to provide an ignitionsystem which can overcomeall the above drawbacks and ensures reliableignition performance.

More particularly, it is an object of the invention to provide anignition system for multi-cylinder internal combustion enginescomprising a plurality of electrically independent ignition powergenerating coils wound on respective main cores arranged side by sidealong a line at right angles to the rotor shaft of a magnet generator,said main cores being magnetically coupled with a pair of auxiliarycores arranged such that the pole pieces of the rotor of said magnetgenerator to pass a magnet flux to these auxiliary cores, said ignitionpower generating coils each being connected in parallel with anassociated ignition coil and with an associated interrupter switch.

According to the invention, it is featured that the disassemblage orreplacement of the ignition power generating coils may be made verysimply, the waste material can be reduced to reduce the material cost ofthe cores, reliable ignition performance free from unbalanced outputs ofthe ignition power generating coils can be ensured, and it is possibleto stack three or more ignition power generating coils together. Thus,the invention provides outstanding benefits in respect of design,performance, cost and assemblage of magnettype ignition systems andmulti-cylinder internal combustion engines using them. i

The invention will now be described in conjunction with a preferredembodiment thereof with reference to FIGS. 4 and 5. Referring to theFigures, a magnet generator is shown having a rotor including a cupshaped magnetic member 1 provided with circumferentially spaced,radially polarized magnets 2 each integral with a pole piece 3. Themagnetic member I is secured to a hub member4 secured to a rotorshaft16, which may be connected to the engine crankshaft. The stator part ofthe magnet generator includes ignition power generating coils 7 and 7'wound on respective main cores 8 and 8' magnetically coupled with a pairof auxiliary cores 5 and 6 arranged to be passed by a magnet flux fromthe pole pieces 3 of the rotor. The cores 8 and 8' are arranged side byside along a line at right angles to the rotor shaft 116. Each of thecores 8 and 8' has its opposite ends snugly received in correspondinggrooves formed in the auxiliary cores 5 and 6 and extending in thedirection of the axis ofthe rotor shaft 16, as shown in FIG. 4. Theauxiliary cores 5 and 6 are secured by bolts 9 to a support base 13.Interrupters l0 and 10' are attached to the support base 10substantially symmetrically with respect to a cam 4a of the hub member4. The support base 10 also carries capacitors 11 and 11. Numeral 12designates a lighting or charging power generating coil disposed on theside of the rotor shaft 16 opposite the ignition power generating coils7 and 7.

FIG. 9 shows the circuit connection of various parts of the ignitionsystem including the magnet generator described above. The ignitionpower generating coil 7 is connected in parallel with interruptercontacts 10, capacitor 11, and the primary winding 18 of an ignitioncoil 21, whose secondary winding 19 is connected to a spark plugelectrode 20. The other ignition power generating coil 7 is connected inparallel with interrupter contacts 10', capacitor 11 and primary winding18' of another ignition coil 21', whose secondary winding 19 isconnected to a spark plug electrode for another cylinder.

Wlth the construction described above according to the invention, inwhich the cores 8 and 8 for the ignition power generating coils 7 and 7are so arranged such that their opposite ends can snugly fit in thecorresponding grooves in the auxiliary cores 5 and 6, the cores 8 and 8and the auxiliary cores 5 and 6 are coupled not only magnetically butalso mechanically. Thus, the cores 8 and 8 and auxiliary cores 5 and 6,though they are separate component parts, may be assembled into anintegral unit, which may then be secured to the support base 13 by bolts9 with extreme ease. Also, it is possible to previously secure theauxiliary cores5 and 6 to the support base 13 and thereafter fit thecores 8 and 8" in them. This means that the present invention systemunlikes the conventional coil arrangement, in order to disassemble orreplace one ignition power generating coil there is no need of removingboth the ignition power generating coilunits, nor'removing the auxiliarycores 5 and 6. In other words, it is possible to carry out thedisassemblage or replacement of the ignition power generating coilsimply, securely and speedily without causing any possible resultantchange of the gap between the pole pieces of the rotor and the auxiliarycores 5 and 6.

' To this end, the ends of the cores 8 and 8 may be of a flared profileas indicated at 8a, 8'a in FIG. 6 and at 8b, 87b in FIG. 7, or they beof a rectangular profile as indicated at 8c, 8c in FIG. 8.

The lamination in the cores 8 and 8' may be widthwise as shown in FIG. 6or thickness-wise as shown in FIG. 7. In either case, the same effectsmay be obtained.

As an alternative construction, one of the cores, for instance core 8may be made integral with the auxiliary cores 5 and 6 so that the othercore 8 may be subsequently fitted.

Since the core 8 or 8' shown in FIG. 6 to 8 has a substantially uniformwidth or thickness over its length, less material is wasted compared tothe conventional cores 15 and 15' shown in FIGS. 1 and 2, greatlycontributing to the reduction of the core material cost.

In the performance aspect, unlike the conventional arrangement of cores15 and 15' axially arranged side by side and spaced apart by spacer 14as shown in FIGS. 1 and 2, the auxiliary cores 5 and 6 according to theinvention may provide a sufficient area to face the pole pieces 3 of therotor, and the magnetic flux may be uniformly distributed to the cores 8and 8, which are securely magnetically coupled with the auxiliary cores5 and 6. Also, the required magnetic flux may reliably pass through eachof the cores 8 and 8'. Thus, even if the ignition power generating coils7 and 7' are obliged to be arranged such that they slightly axiallydeviate from the pole pieces 3 of the rotor, outputs of the samemagnitude may be obtained from the ignition power generating coils 7 and7 so that reliable performance of the ignition system may be ensured.

Further, three or more ignition power generating coils may be readilyprovided without altering the axial dimension of the rotor.

Furthermore, although the preceding embodiment is concerned with anoutside rotor type magnet generator, the core construction andarrangement according to the invention may of course be applied toinside rotor type magnet generators.

What is claimed is:

1. In an ignition system for multi-cylinder internal combustion engineshaving ignition coils, interrupters, and a magnet generator with atleast two ignition power generating coils independent with each other,said magnet generator comprising:

a rotor including a rotor shaft and a plurality of magnetic pole pieces,said pole pieces being disposed on said rotor with predeterminedseparations;

a stator arranged with a coaxial relationship with said rotor;

a pair of auxiliary cores disposed on said stator so as to be capable offacing towards said pole pieces of said rotor;

at least two main cores, connected to said pair of auxiliary corestherebetween in parallel relation with each other, for magneticallycoupling said respective auxiliary cores so as'to pass a magnetic fluxfrom said pole pieces therethrough, said main cores being arranged sideby side on the same side of said rotor shaft and on a planeperpendicular to the axial direction of said rotor shaft;

said ignition power generating coils being wound on said respective twomain cores, whereby electromotive forces are generated in saidrespective ignition power generating coils independently andsimultaneously as said rotor rotates.

2. An ignition system according to claim 1, wherein the ends of saidmain cores are a flared profile.

3. An ignition system according to claim 1, wherein the ends of saidmain cores are a rectangular profile.

1. In an ignition system for multi-cylinder internal combustion engineshaving ignition coils, interrupters, and a magnet generator with atleast two ignition power generating coils independent with each other,said magnet generator comprising: a rotor including a rotor shaft and aplurality of magnetic pole pieces, said pole pieces being disposed onsaid rotor with predetermined separations; a stator arranged with acoaxial relationship with said rotor; a pair of auxiliary cores disposedon said stator so as to be capable of facing towards said pole pieces ofsaid rotor; at least two main cores, connected to said pair of auxiliarycores therebetween in parallel relation with each other, formagnetically coupling said respective auxiliary cores so as to pass amagnetic flux from said pole pieces therethrough, said main cores beingarranged side by side on the same side of said rotor shaft and on aplane perpendicular to the axial direction of said rotor shaft; saidignition power generating coils being wound on said respective two maincores, whereby electromotive forces are generated in said respectiveignition power generating coils independently and simultaneously as saidrotor rotates.
 1. In an ignition system for multi-cylinder internalcombustion engines having ignition coils, interrupters, and a magnetgenerator with at least two ignition power generating coils independentwith each other, said magnet generator comprising: a rotor including arotor shaft and a plurality of magnetic pole pieces, said pole piecesbeing disposed on said rotor with predetermined separations; a statorarranged with a coaxial relationship with said rotor; a pair ofauxiliary cores disposed on said stator so as to be capable of facingtowards said pole pieces of said rotor; at least two main cores,connected to said pair of auxiliary cores therebetween in parallelrelation with each other, for magnetically coupling said respectiveauxiliary cores so as to pass a magnetic flux from said pole piecestherethrough, said main cores being arranged side by side on the sameside of said rotor shaft and on a plane perpendicular to the axialdirection of said rotor shaft; said ignition power generating coilsbeing wound on said respective two main cores, whereby electromotiveforces are generated in said respective ignition power generating coilsindependently and simultaneously as said rotor rotates.
 2. An ignitionsystem according to claim 1, wherein the ends of said main cores are aflared profile.